Islands Helped Penguins Evolve. Then Hungry Humans Showed Up.
For thousands of years, penguins have darted through the waters of the southern oceans, chasing fish and surfacing to nest on islands and landmasses sprinkled from the Galápagos to the Antarctic. Today there are around 20 penguin species, ranging from the playful Adelie to the stately Emperor. But there once were other penguins, including a previously unknown subspecies of dwarf yellow-eyed penguin in New Zealand.
You won’t be seeing it any time soon. It’s extinct, apparently wiped out by humans hundreds of years ago.
“We suspect that these Megadyptes penguins were on their way to becoming a full new species,” said Theresa Cole, a graduate student at University of Otago in New Zealand and co-author of a paper about this bird and another newly discovered extinct subspecies of crested penguin. “But they just didn’t get a chance, because people ate them.”
With their family tree, Ms. Cole and her fellow researchers set out to understand when it was that these birds started to diverge from each other. The researchers linked the tree to the dates assigned to fossilized penguins, and from that, they were able to deduce the rough timing of the penguins’ radiation into different species over millions of years.
That revealed something intriguing. Many penguins are native to specific volcanic islands, which arose relatively quickly from solidified lava. Often, the researchers found, the appearance of new penguin species was closely tied in time to the appearance of those penguins’ native islands. In other words, before the islands formed, the species that call them home today did not exist. Rather, these species came into being when penguins from elsewhere popped out of the sea near the new patches of earth, began to make a new life for themselves, and slowly evolved into a new species.
The dwarf yellow-eyed penguin and the new crested penguin were natives of the Chatham Islands in southern New Zealand. The dwarf penguin was genetically very similar to the yellow-eyed penguins that currently roam New Zealand’s mainland. But the little creatures were even smaller than the yellow-eyed penguins, which are only a couple of feet tall.
The bones of both penguins have been found in trash heaps that date back to when humans arrived in the Chatham Islands. Circumstances suggest that the animals were cooked and eaten, and they soon went extinct.
They would not have been the first island birds to suffer from the arrival of ravenous bipeds, and sadly, they were not the last. In recent years, penguin numbers around the world have plummeted. One recent study projected that by 2060 the yellow-eyed penguins still living in New Zealand may join their dwarf relatives in extinction, unless an effort is made to preserve them.
“Throughout the southern hemisphere, in particular in the Pacific, penguin populations are declining,” said Ms. Cole. “Pretty much all of the penguins that are endemic to New Zealand are faced with various threats including fishing, and pollution, and warming sea surface temperatures, and competition with humans, dogs eating penguins, habitat fragmentation. Even though humans aren’t eating them anymore, there are other impacts that will keep driving them to extinction.”